August Weismann

August Weismann (17 January 1834-5 November 1914) was a German evolutionary biologist who performed an experiment on mice in an attempt to disprove the idea of heredity. He cut the tails off of mice, had them mate 400 times, and discovered that the tailless mice always made mice with tails.

Biography
August Weismann was born in Frankfurt am Main in 1834, and he opened a medical practice in 1868. He went on to work as a professor at Albert Ludwig University from 1873 to 1912, and he experimented on the inheritance of mutilations with mice, cutting their tails off and breeding them; he discovered that acquired traits cannot be inherited, as all of the offspring had normal-length tails. He also discovered the germ plasm theory, in which inheritance only happens through germ cells, and not through somatic cells, and that information can not pass from soma to germ plasm and on to the next generation, the Weismann barrier; this ruled out Jean-Baptiste Lamarck's theory of inheritance of acquired characteristics.